Due to global warming grapes worldwide contain more sugar. This sugar is converted to alcohol in the alcoholic fermentation, resulting in wines with increased alcohol levels.
In line of this, one of the major problems in the wine industry today is the high ethanol levels. Ethanol levels at 15-16% (V/V) destroy the sensorial quality of a wine and sometimes put the wine into a higher tax classification than intended. The elevated ethanol levels seen over the last decades are a consequence of rising sugar levels in harvested grapes. Today, wines with an ethanol content above 16% (V/V) are no longer a rarity, and sugar levels are forecasted to increase even more with the global warming.
Important wine areas that are currently believed to be negatively affected by the global warming are important areas such as Rioja (Spain), Chianti (Italy), Hunter Valley (Australia) and Southern California.
Current methods for ethanol reduction like reverse osmosis, spinning cone or dilution are not satisfactory. These methods may have adverse effects on the sensorial quality of the wine. Furthermore is the price of up to 1 USD/gallon for re-verse osmosis of wine a major limitation for a wider use of this approach.
U.S. Pat. No. 4,675,191 (Novo Industri, Denmark—published 1987) describes a method for reducing alcohol content in wine that involves use of the enzyme glucose oxidase. With respect to the described method column 2, lines 25-29 read:                “The method of this invention comprises treating unfermented grape juice with glucose oxidase in the presence of oxygen, thereby converting glucose in the grape juice into gluconic acid and thereafter fermenting the so-treated grape juice.”        
The herein main relevant technical elements of this prior art method are schematically illustrated in FIG. 1.